


domino effect

by ilyasomina



Category: Supernatural
Genre: Alternate Universe Sam & Dean, Canon Divergence, Dean Winchester Has a Sexuality Crisis, Demon Blood Addict Sam Winchester, Dimensional Portals, Female Sam & Dean Winchester, Implied/Referenced Character Death, Implied/Referenced Child Abuse, M/M, from an alternate dimension, is this making sense?
Language: English
Status: In-Progress
Published: 2021-03-13
Updated: 2021-03-14
Packaged: 2021-03-21 16:40:57
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,409
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/30024717
Author URL: https://archiveofourown.org/users/ilyasomina/pseuds/ilyasomina
Summary: "Except a portal opened in the library," Dean snaps into to phone. "And me and Sam from another dimension fell through, but we're girls, and we're about ten years younger, and I'm pretty sure you're MIA."There's silence. "Oh," Castiel finally says."Yeah. Oh."-Dean has a bit of self reflecting to do. With, you know, himself,andthe gender bent version of himself from another dimension, whose got a piss poor attitude, angel's grace, and a lot of differing opinions.
Relationships: Castiel/Dean Winchester
Comments: 8
Kudos: 25





	domino effect

**Author's Note:**

> there is a playlist that goes along with this fic that you can find [here on spotify!](https://open.spotify.com/playlist/428L0VG5F47YHp81KEYe6T?si=PPZQ3FJeSR-u4VJ_A4Thqg) if you're curious, [this is how i picture girl!sam](https://i.pinimg.com/564x/0f/f9/05/0ff90551d950e94cf940d14f78584c80.jpg) and [this is how i picture girl!dean.](https://i.pinimg.com/750x/53/4b/46/534b46abccfe0c82b2c123bc89f481b6.jpg)
> 
> i'd say this takes place early/mid s15, where chuck hasn't been defeated yet and is busy destroying other dimensions in that weird radio shack. timeline is not that important, just that it's s15 and jack has already been brought back. believe it or not i came up with this au before i saw the episode where au sam and dean came to the bunker and fruited up the place.

The problem, Dean thinks, in retrospect, is that the bunker is not warded against dimensional portals.

This technically shouldn’t be an issue in the first place. He’s not sure if the Men of Letters knew about alternate dimensions, and if they didn’t, they definitely didn’t have any warding instructions in the thousands of books they left behind. But since they know about it  _ now,  _ Dean thinks they should probably invest in figuring out how to ward the bunker against them. So portals stop opening up in the middle of it and alternate versions of he and Sam stop stepping out.

Dean has none of these rational thoughts when a new portal opens in the library. In fact, the first thing he thinks is,  _ what the hell?.  _ The first thing he says out loud is, “What the fuck?” as the fabric of space and time is ripped open with a terrible zipping noise and lights up gold and glittery. Unlike last time, when prim and proper versions of themselves stepped out of a laughable tiny car dressed to the nines,  _ this  _ time two girls come tumbling through like they’ve been bodily thrown into it. The first one comes out limply, sliding on the wooden floor on her back and landing a few feet away, body still and unmoving. A split second later another girl comes smashing through, tuck and rolling neatly to catch herself.

Her head snaps around, and she barely blinks at her surroundings, eyes roaming right over Sam and Dean, who are sitting at one of the tables with blank looks of shock. She scans the room, and when her gaze lands on the body of the other girl she dives for her like her life depends on it.

“Okay, okay, okay,” She mumbles. She scrambles to check the limp girl’s pulse, hastily pushing the hair from her forehead to check her temperature at the same time. “Okay, I got this, big girl, hang on-”

The girl reaches into her pocket and pulls out a switchblade. Without blinking, she slices open a large gash across her right palm, teeth gritting against the pain.

“What the fuck?” Dean says again. Sam gives him an equally startled look. The girl doesn’t even acknowledge them, and instead begins dragging her hand along the floor, clearly drawing some sort of symbol in her own blood.

Sam recognizes it first, because he shoots up out of his seat and says, “Hang on a minute-” just a few seconds before Dean realizes she’s drawing a demon summoning sigil.

The girl rears up like a snake coiling to strike when Sam approaches her, and in the same move reaches into the inside of her denim jacket and pulls out an angel blade, pointing it at Sam threateningly. 

“Fuck off,” She snarls, her voice leaving no room for argument.

Sam raises his hands in the universal sign of surrender, switching to the placating, calming voice he uses on feral victims they find on cases. “Hey, okay, let’s just all calm down here.”

“I am calm,” The girl snaps, going back to drawing the sigil but keeping the blade pointed in Sam’s general direction.

Beside her, the other girl suddenly jerks violently. Her whole body twitches, and she lets out a noise that sounds like a pained moan.

The girl with the blade shushes her gently, clenching her hand tightly to squeeze out more blood as she chants a summoning spell and finishes up the sigil. A split second later there’s a  _ whoosh  _ and a demon in the form of a young man appears in the circle, it’s eyes blinking completely black as it takes in the room.

“What-” It begins, but it doesn’t have time to finish- The girl dives for it with all the ferocity of a lioness taking down its prey. She slices it’s throat with quick precision, and it’s body crumples to the floor, it’s voice gurgling oddly as blood spills everywhere. With a practiced ease, she cups her hands to it’s throat, collecting a pool of blood in her palms. Beside her, the other girl lets out another moan, high-pitched and bordering on a scream.

“Okay, I gotcha,” The girl says. Her hands tremble as she brings them to the other girl's lips, tilting her head back and letting the blood pour down her throat. “There you go.”

Dean shoots Sam a look, where the younger man has frozen to the spot, looking pale as he watches the scene unfold.

The demon’s throat bubbles sickly as it tries to speak. The girl ignores it as she continues to feed the unconscious girl it’s blood. When she’s finished, she barely even takes her eyes off the other girl as she drops her hands and instead moves them to the demon’s forehead. Her eyes glow a hot white blue color, and light flashes from her hands, and just like that she’s smited it.

_ Angel, _ Dean thinks.  _ This isn’t a girl, it's an angel. _

A silence falls over the room as the angel slumps down, pressing her forehead to the unconscious girl’s chest and letting out a heavy sigh of relief. Dean swears he can hear the clock in the kitchen ticking from here, with how tense and quiet it suddenly becomes.

“Excuse me,” Sam finally says, voice gentle. He takes another step towards the angel. “Are you okay?”

That wasn’t what Dean would’ve chosen to say, but it was a valid question.

The angel lifts her head and finally seems to actually notice her surroundings. She looks young, in her twenties maybe, with long hair and sharp green eyes; she’s got demon blood smeared on her forehead and chin, and her hands were absolutely coated in it.

She cranes her neck to look up at Sam, and after a moment, she flashes him a tired looking smile, winking.

“I’m fine, handsome,” She replies, but her voice betrays her by cracking on the compliment. “Are  _ you _ okay?”

“You’re the one who just busted through a portal and killed a demon for it’s blood in the same breath,” Dean says. The angel’s eyes flicker to his, and her gaze reminds him of someone- like she’s wearing someone else’s eyes on a stranger’s face.

“Portal?” She repeats. She looks around the room again, thoroughly this time, taking in the shelves and shelves of books, the war room and stairs and entrance to the hall. Her lips move as though she’s talking to herself silently, and then her eyes snap back to Dean’s. “Portal?”

“Yeah, a portal,” Sam begins. He takes another step towards her, and her gaze turns icy, her body hunching over the other girl’s. He keeps his hands up in surrender even as he approaches her, like a wild, injured animal. “You guys just fell through a dimensional portal.”

She doesn’t look as shocked as she should. Instead, she blinks slowly at him as she processes his words. Then she laughs bitterly.

“Of fucking course we did,” She mutters, half to herself. “You hear that, Sammy?” She looks down at the girl, face going gentle. She reaches out to push the girl’s hair from her forehead, smearing blood along her skin. “Michael really fucked us on this one.”

“Michael?” Sam repeats, the same time Dean says, “Sammy?”

The angel looks at him quizzically, and in the same breath, realization dawns over her face, like she’s come to some great conclusion only she can see. She laughs again, and begins getting to her feet.

“Name,” She says, pointing the angel blade like an accusatory finger at Dean. 

Dean frowns at her. “Why don’t you tell us  _ your  _ name? Since, you know, you are in our home.”

The angel raises an eyebrow. “This is your  _ home _ ? It looks like a doomsday bunker.”

“I mean, it is a bunker,” Sam says under his breath.

“That’s irrelevant,” Dean snaps.

“What’s your name?” The angel repeats. 

“Yours first.”

They hold each other’s gazes, the space between them charged and tense. Dean refuses to back down, but so does the angel, until finally Sam huffs out an impatient breath.

“I’m Sam,” He says, ignoring the dirty look Dean shoots him. “This is my brother, Dean.”

The angel barks out a harsh sounding laugh. “Winchester?” 

“Do you know us?”

The angel tucks her blade back inside her jacket, wiping the blood on her hands off on her jeans and holding out stained red palm for Sam to take. “Deanna Winchester,” She jerks her head towards the girl on the floor. “This is my sister, Sammy.”

Sam looks pale again. “What?”

“What?” Dean repeats.

Deanna grins, teeth sharp. “Yeah.”

They move Sammy to a guest room, at Deanna’s insistence, before they sit down to talk. Sammy is completely out cold, mouth and neck smudged with dried demon blood. It barely looks like she’s breathing to Dean, but the other girl insists she’ll wake up within the hour.

“So, what I’m understanding,” Sam says as Deanna pokes around the kitchen, inspecting cookware and cereal boxes like she’s never seen them before. “Is that you’re female versions of us from another dimension.”

“Or you’re male versions of us,” Deanna corrects, flashing him a smile. She finds Jack’s box of Cookie Crisp and cracks it open without a word, shoving her hand in to pull a handful out.

“Or… that,” Sam frowns and turns to Dean. “I thought Chuck destroyed all the other dimensions?”

“Chuck?” Deanna echoes through a mouthful of cereal.

“God,” Dean grimaces. Deanna chokes.

“God’s name is  _ Chuck?”  _ She exclaims, and Dean thinks it’s funny that’s what she focuses on.

“Yeah, uh,” Sam’s got a furrow between his brow like he’s figuring out a particularly tough math problem. “He’s not a nice guy.”

“Well, destroyer of dimensions or not, he missed ours,” Deanna says, abandoning Jack’s cereal and turning her attention on Sam’s expensive espresso maker. “And I need to get me and Sammy back asap.” 

“So, about that,” Sam fixes Deanna with a curious look. “How did you get through the portal? Or open it at all?”

Deanna finally takes a seat beside Dean, but she fidgets restlessly, her long fingers tapping against the tabletop.

“Uh. Well,” She looks between the two of them, expression hesitant. “You guys have, uh… you know. Michael here?”

“The archangel?” Sam asks.

“Notorious asshole?” Dean adds.

Deanna snorts. “Yeah, that’s the one. And the whole sword shit…?” She trails off, glancing at Dean pointedly.

Dean makes a face, remembering nearly a decade ago when angels were going to the ends of the earth to get him to say yes to Michael. To just a few years ago, when Michael from the apocalypse world tricked him into saying yes and made Dean’s own mind a living hell.

“Yeah, I was supposed to be his sword, too,” Dean finally says, slowly, shaking off the phantom feeling of having both his lungs removed by Zachariah. Deanna’s eyes sharpen, probably at the _ ‘was’, _ but she doesn’t comment on it.

“Well, he keeps trying to get me to say yes,” She continues. “I mean, it’s impossible, even if I did, but he thinks if I do he’ll be able to-”

“Wait,” Sam interrupts. “Why is it impossible?”

Deanna’s face goes blank impressively quick. “What?”

“You said it’d be impossible even if you said yes,” Dean elaborates. “Why would it be impossible?”

Deanna doesn’t respond. She just stares at them, face blank of any emotion that could give them the barest hint of what she was feeling, until the silence becomes almost uncomfortable between them. 

Sam opens his mouth, but before he can speak there’s the sound of something breaking loudly down the hall. Dean nearly jumps out of his seat, and Deanna lets out a sigh.

“That’ll be Sammy,” She says, getting to her feet.

They all move from the kitchen to the guest room they had placed Sammy in. Inside, the other girl stands in the corner of the room. She’s broken one of the front legs of the bed frame, splintered it off so it now resembled a stake. She points it at Sam and Dean, eyes flickering between them and Deanna.

“Sammy,” Deanna says in an almost amused voice. “Whatcha doin’?”

Sammy glares at her, and Dean stops himself from cursing out loud, heart picking up when he catches her eyes- they’re fully black, like a demon’s, glittering in the low light of the room.

“You broke these nice boys’ bed,” Deanna continues, approaching Sammy like an animal keeper would a feral lion in it’s care. “That’s no way to thank them for their hospitality.”

Sammy doesn’t break her scowl, eyeing Sam and Dean warily. “Who are they?” She asks, and her teeth glint with dried demon blood.

“Friends,” Deanna says, stopping in front of Sammy to gently pry the faux-stake from her hands. “Put your eyes away, Sammy, you’re freaking them out.”

Sammy blinks slowly. The black retreats from her eyes and reveals a normal green color, similar to Deanna’s. Similar to Dean and Sam’s own. Much to Dean’s chagrin, Sammy is tall, almost as tall as him, and definitely taller than her older sister, who stands at Sammy’s chin and comes to Dean’s shoulders. She’s got black hair lobbed short into a bob and sharp features, and though she puts away her demonic eyes and easily lets Deanna take the stake, her posture stays tight and alert as she takes in the rest of them.

“Who are they?” Sammy demands again. The blood on her face is dried and smeared across her cheek, and it reminds Dean of when he saw Sam drink the same type of blood years ago. Unlike Sam, Sammy doesn’t look at all embarrassed or horrified that she’s been seen drinking it. 

“This is Dean,” Deanna says, voice still careful and collected like she thinks Sammy might pounce. “And Sam. We’re in their home.”

Sammy’s eyes flicker to the bare walls and military style furniture. “Home?”

“Bunker,” Sam corrects. Sammy turns her glare on him, and he takes a step back, looking surprised.

“Why don’t we go get you some water, and we can talk about what happened?” Deanna asks, placing a gentle hand on Sammy’s lower back. Despite her hesitancy, Sammy moves easily where Deanna guides her. Dean and Sam step out of their way as they pass, and Sam gives Dean a bewildered look. Dean is sure his face looks similar, and so they follow the girls to the kitchen.


End file.
